The Great Cold Spot in the cosmic microwave background

The Great Cold Spot in the cosmic microwave background: The CMB cold spot is not particularly colder than other cold regions of the CMB, but it is unusual because it is a particularly cold region surrounded by a rather warm region. Simulations of random fluctuations in a CMB estimate that the odds of such a cold spot happening in the universe is about 1 in 100. So it's possible that it is just a random fluctuation. But the 1% odds is small enough that some astronomers have looked for a possible cause, and these ideas have ranged from the mundane to the wild.